Automotive powered seat positioning mechanisms are known of the type using a threaded spindle engaged by a gear nut carried by an upper track, with the gear nut driven by a worm gearing in turn driven by a motor. Rotation of the gear nut causes the gear nut and an enclosing gear case to drive the upper track so as to be advanced in either direction along the spindle. Such mechanisms are described in U.S. Pat. No. 4,802,374 and WO 9951456.
The gear nut and worm gear are typically carried in a gear casing mounted on a U-shaped bracket having its legs attached to the upper track to cause the movement of the gear nut to drive the upper track in either direction. The spindle is mounted spaced above the bottom wall of a lower track on a pair of brackets each located at an opposite end of the spindle, these brackets in turn attached to the lower track.
The automobile seat is held in any adjusted position by the gear nut and spindle and these components are thus subjected to high loads in the event of a crash or other high stress event and the support for these components must therefore be designed to have adequate strength to resist the stresses imposed.
It is desirable that the seat adjustment mechanism be fully functional after a crash.
The bracket supporting the gear nut and gear casing tends to be distorted as the upper track supporting the seat and the occupant tends to move forward in a crash or other high stress event, and this is resisted by the gear nut-spindle engagement, applying of forces offset from the point of attachment to the upper track. The unattached lower ends of the legs of the bracket cannot effectively resist these forces. The bottom location of the leg connecting portion of the bracket prevents any fastener attachment to the side walls of the upper track after assembly since that portion is then completely inaccessible. Thus, heavy gauge steel must be employed to construct the bracket to resist the forces applied in this manner.
The spindle itself must be well anchored to resist these stresses, which typically is done by a heavy gauge bracket mounted at each end of the spindle. These sturdy brackets must in turn be securely attached to the lower track.
It is the object of the present invention to provide a track assembly in which the connection between the bracket and the upper track provides a balanced loading of the bracket which efficiently resists the forces imposed thereon in a crash or other high stress event.
It is another object to simplify the attachment of the spindle to the lower track while still providing ample strength to withstand the crash induced stresses imposed thereon.